If I have a choice between an acid dispenser or a CO2 dispenser for Sense and Dispense, which should I go with? My pH is always rising from jets but my TA is often rising too. It's gone from 50 to 100 in just a few days.
Crazy ph
- Thread starter christianday
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CO2 is best when the pH rises and the TA is not changing. Acid is best when both pH and TA are rising. However, if your plaster gets sealed, then your pool would mostly have just pH rise from carbon dioxide outgassing when the swim jets are on.
I worry about that, chem geek. Since I first started testing this pool, both TA and pH have been rising. I am wondering if it's better to start out with acid. I believe the Sense and Dispense can work with either. I'm not sure how they hook up but I can always get the Stener acid tank and a CO2 tank.
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I mean, if I keep the acid dosing low enough, I can't imagine it's going to drop the TA too much. The two always seem to move in relative unison. The Sense and Dispense has a nifty timeout feature so if the probe's malfunctioning, you can set a time after which it stops dispensing acid altogether and I'll probably do a short time frame like ten minutes or something, after which it shuts down until you manually tell it to start up again, presumably after testing the water. Reading the manual, it looks like a great tool. I may even try the ORP though people say it doesn't work. Our chlorine is usually perfect. Even the Leslie's people said so, so my % adjustments seem to be working but I think it doesn't hurt to try it.
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Also, I was just reading that if the TA is too high, the CO2 won't be enough to lower the pH. I may start with the acid and switch to the CO2 if the plaster ever stops bleeding whatever it's bleeding. The main sense and dispense system is compatible with either. Plus I'm replacing the water. If I keep the pH on the high (7.8) end, then maybe the TA won't be too affected by the acid?
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I mean, if I keep the acid dosing low enough, I can't imagine it's going to drop the TA too much. The two always seem to move in relative unison. The Sense and Dispense has a nifty timeout feature so if the probe's malfunctioning, you can set a time after which it stops dispensing acid altogether and I'll probably do a short time frame like ten minutes or something, after which it shuts down until you manually tell it to start up again, presumably after testing the water. Reading the manual, it looks like a great tool. I may even try the ORP though people say it doesn't work. Our chlorine is usually perfect. Even the Leslie's people said so, so my % adjustments seem to be working but I think it doesn't hurt to try it.
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Also, I was just reading that if the TA is too high, the CO2 won't be enough to lower the pH. I may start with the acid and switch to the CO2 if the plaster ever stops bleeding whatever it's bleeding. The main sense and dispense system is compatible with either. Plus I'm replacing the water. If I keep the pH on the high (7.8) end, then maybe the TA won't be too affected by the acid?
Since you have high TA fill water and since the swim jets are likely to exacerbate evaporation and refill, then using acid would probably be better. However, because CO2 outgassing will also be exacerbated by the swim jets, your TA will drop over time from acid addition and you'll need to bring the TA back up using baking soda. To minimize the CO2 outgassing you'll probably target a lower TA, higher pH, and have a higher CH to compensate for the saturation index but this is all for later after the plaster gets sealed (if it can get sealed).
You are right that the TA drops in direct proportion to the amount of acid that you add. However, it doesn't matter whether you add a little at a time or more at once unless your acid addition gets the pH significantly lower in which case the CO2 outgassing then goes faster requiring you to add even more acid. So hopefully targeting a higher pH and doing more of an acid dribble might help. It will also help if such automatic dispensing doesn't strip the calcium carbonate from the plaster which your manual addition might have done if you did not slowly pour the acid over a return flow and lightly brush the side and bottom of the pool to ensure thorough mixing.
So go ahead and start with their acid system. As for the TA effect from the acid, again in your 10,000 gallon pool adding 25-1/2 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) will lower the TA by 10 ppm. What a higher pH target and lower TA target should do is lower the amount of CO2 outgassing which should lessen the rate of pH rise from that, but it won't help with the pH and/or TA rise from the plaster. That problem has to be dealt with by sealing the plaster (forming a solid calcium carbonate layer so that calcium hydroxide is no longer exposed to the water).
You are right that the TA drops in direct proportion to the amount of acid that you add. However, it doesn't matter whether you add a little at a time or more at once unless your acid addition gets the pH significantly lower in which case the CO2 outgassing then goes faster requiring you to add even more acid. So hopefully targeting a higher pH and doing more of an acid dribble might help. It will also help if such automatic dispensing doesn't strip the calcium carbonate from the plaster which your manual addition might have done if you did not slowly pour the acid over a return flow and lightly brush the side and bottom of the pool to ensure thorough mixing.
So go ahead and start with their acid system. As for the TA effect from the acid, again in your 10,000 gallon pool adding 25-1/2 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) will lower the TA by 10 ppm. What a higher pH target and lower TA target should do is lower the amount of CO2 outgassing which should lessen the rate of pH rise from that, but it won't help with the pH and/or TA rise from the plaster. That problem has to be dealt with by sealing the plaster (forming a solid calcium carbonate layer so that calcium hydroxide is no longer exposed to the water).
The first mistake is adding salt before 30 days. Putting the salt in a new plaster pool before it has cured 30 days creates the very problems you are seeing, such as a rapid rising pH. However, that negative effect should have discontinued after about 30 days.
See this thread. When Should Salt be Added?
That study on adding salt showed that the rapid increase in pH (caused by high salt content) ended within a month after the pool was completed and filled with water. But of course, that experiment was performed on quality pool plaster.
Secondly, it may be that your plaster contractor made the mistake of adding a lot of calcium chloride to the plaster mix. That also contributes to an increase in CH, TA, and pH after filling with water. A high water/cement ratio and water-troweling does the same too. Those issues that I just mentioned creates poor quality pool plaster. It could be that your plaster mix and application may not be of the best quality, and therefore, the combined effect is why you may be continually having to deal with an above normal pH and TA rise. It does seem amazing that this is still happening after 4 months, but I suppose it is possible given what we know about poor quality plaster.
Chem geek's suggestion that the plaster surface needs "sealing" by performing a Bicarb start-up is a plausible solution and just could be the answer. However, given that your CH is above 350 ppm (along with the current TA), I would believe that the "carbonation" process would have easily occurred within the past two months.
That brings up another question that I have. If your tap water contains only 175 ppm of calcium, and now it is somewhere around 400 ppm, did anyone add calcium to increase the CH when the pool was first filled with water? If no one has added calcium, then that is another indicator of possible poor quality plaster. Of course, when water is aggressive, that is another way for the calcium content to increase.
At this point, my suggestion is to give it a few more weeks to see if there is any change.
See this thread. When Should Salt be Added?
That study on adding salt showed that the rapid increase in pH (caused by high salt content) ended within a month after the pool was completed and filled with water. But of course, that experiment was performed on quality pool plaster.
Secondly, it may be that your plaster contractor made the mistake of adding a lot of calcium chloride to the plaster mix. That also contributes to an increase in CH, TA, and pH after filling with water. A high water/cement ratio and water-troweling does the same too. Those issues that I just mentioned creates poor quality pool plaster. It could be that your plaster mix and application may not be of the best quality, and therefore, the combined effect is why you may be continually having to deal with an above normal pH and TA rise. It does seem amazing that this is still happening after 4 months, but I suppose it is possible given what we know about poor quality plaster.
Chem geek's suggestion that the plaster surface needs "sealing" by performing a Bicarb start-up is a plausible solution and just could be the answer. However, given that your CH is above 350 ppm (along with the current TA), I would believe that the "carbonation" process would have easily occurred within the past two months.
That brings up another question that I have. If your tap water contains only 175 ppm of calcium, and now it is somewhere around 400 ppm, did anyone add calcium to increase the CH when the pool was first filled with water? If no one has added calcium, then that is another indicator of possible poor quality plaster. Of course, when water is aggressive, that is another way for the calcium content to increase.
At this point, my suggestion is to give it a few more weeks to see if there is any change.
Hi chem geek and onBalance: can you give me in the most basic english for my pool builder what a bicarb start-up is? Maybe that will help all this. Anything that will avoid re-plastering the pool.
Also, I don't think calcium was added but I will ask. But that definitely makes sense that it's plaster. I will ask specifically about the salt but it was definitely before the 30 days.
Definitely getting an acid sense and dispense. I can go down the street to the hardware store anytime I need to refill the tank and it's easy enough to throw baking soda in there without risking acid burns and fumes.
Thank you! You all really rock.
Christian
Also, I don't think calcium was added but I will ask. But that definitely makes sense that it's plaster. I will ask specifically about the salt but it was definitely before the 30 days.
Definitely getting an acid sense and dispense. I can go down the street to the hardware store anytime I need to refill the tank and it's easy enough to throw baking soda in there without risking acid burns and fumes.
Thank you! You all really rock.
Christian
See the thread A Bicarb Start-up guide for TFP members. Basically what it does is somewhat over-saturates the pool water with calcium carbonate and in particular makes sure there is enough TA (bicarbonate) in the water so that any calcium hydroxide in pool plaster can get converted into calcium carbonate in-place. The pH is allowed to be kept higher in the 7.6 to 8.2 range. The rough rule-of-thumb is that the sum of CH and TA is around 500.
What we would do at this point is get the TA higher, but keep your swim jets off. As we added acid to keep the pH below 8.2, we would as needed add baking soda to maintain the higher TA. We would then hopefully see 1) the TA and CH no longer rise and 2) the pH slow down in its rise. If that happens, then the plaster is getting sealed with calcium carbonate. If that doesn't happen, then you are no worse off, but it means your plaster is toast and not able to be repaired without some sort of replacement (maybe because there was too much calcium chloride in the initial mix). If you wanted to live with the existing plaster, then you'd have the automated acid dosing still adding a lot of acid over time and you'd manually be adding baking soda on occasion to maintain the TA level. The plaster may become more pocked and rougher as the calcium hydroxide continued to dissolve. The harder calcium silicate hydrate would remain, but without the supporting calcium carbonate in between it could be susceptible to further degradation (breakage).
What we would do at this point is get the TA higher, but keep your swim jets off. As we added acid to keep the pH below 8.2, we would as needed add baking soda to maintain the higher TA. We would then hopefully see 1) the TA and CH no longer rise and 2) the pH slow down in its rise. If that happens, then the plaster is getting sealed with calcium carbonate. If that doesn't happen, then you are no worse off, but it means your plaster is toast and not able to be repaired without some sort of replacement (maybe because there was too much calcium chloride in the initial mix). If you wanted to live with the existing plaster, then you'd have the automated acid dosing still adding a lot of acid over time and you'd manually be adding baking soda on occasion to maintain the TA level. The plaster may become more pocked and rougher as the calcium hydroxide continued to dissolve. The harder calcium silicate hydrate would remain, but without the supporting calcium carbonate in between it could be susceptible to further degradation (breakage).
The TA and pH are god knows what now but they were 100/>8.2 a couple days ago. My builder is coming Thursday with people to look into it. If they have to replaster it, so be it. I know we weren't brushing past the initial phase because we didn't realize we were supposed to.
Also, I'm having them show me how to clean the filters. We get termite swarms here and they do die in the pool. We'll end up skimming thousands out (not kidding). I can only imagine what those do to the chemistry in the filter. All those bugs are made up of something.
Also, I'm having them show me how to clean the filters. We get termite swarms here and they do die in the pool. We'll end up skimming thousands out (not kidding). I can only imagine what those do to the chemistry in the filter. All those bugs are made up of something.
Oh, and our builder did wait 30 days to add salt. They used a chlorinator until then.
Today I did a half gallon of MA, diluted in a five gallon drum of water, and it managed to bring the TA from 100 to 90 and the pH was still above 8.2. Who knows where it must have been before, but the sense and dispense with acid module is on its way. If we get the TA from being the crazy thing that it is, we'll probably switch to CO2.
So the Pool Builder is going to be scheduling a time to drain the entire pool and refill without borates and install a sense and dispense with acid. Until then, I've been using dry acid, but two entire 5lb jugs of pH down only brought the pH down to 7.7 yesterday and it's already probably in the 9's so I had to add another jug. This is unbelievable but the borates make you have to add way more than even pool calculator seems to say to add. Either that or the pH is so high above 8.2 that there's just no getting around it. I may have the pool re-plastered. I wish I could have figured all this out. I'm ready to fill the pool in. We never ever get to just enjoy it anymore.
Reading between the lines, is the pool builder taking no responsibility for problems with the plaster? What is his explanation for the very atypical chemistry of your new pool?
singingpond: that is the $64,000 question. I think he will charge me for the plaster to be replaced, which I suppose I'll give him since I added borates, but I think the problem may be how I added acid in the beginning because he never told me how to do anything. He said we might have to shock the pool once every year or two and that's it. He said nothing about pH at all and knows nothing about it. I'm pretty upset about it but there's nothing I can really do. I spoke to a person tonight who maintains commercial pools and he was the first person I spoke to who knew anything about CO2 outgassing or aeration raising ph or plaster leeching or any of that so I'm going to get him to come by if the pool builder doesn't hurry up and drain this pool like he's supposed to. This new guy didn't know about borates but that really doesn't seem to be a widespread practice. It does look like it normally works but in my case, it's only slowing the drop in pH, not the rise, so the only change to my situation with borates it that I now have to add four times or more as much acid as I did before to lower the pH but it rises just as fast as it ever did, if not faster. My thought is that this additional acid requirement is probably also screwing with the plaster.
The pool builder mentioned doing an acid wash when they drain the pool, which I don't fully understand if that's how we ended up here to begin with.
The pool builder mentioned doing an acid wash when they drain the pool, which I don't fully understand if that's how we ended up here to begin with.
Oh my goodness! I am just now seeing this thread and I just want to you give you a big ole Texan "bless your heart." My husband would have been THROUGH THE ROOF if all of that had happened with our pool build.
Here's wishing all goes well for you!
[emoji176] Lisa P.
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Here's wishing all goes well for you!
[emoji176] Lisa P.
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It is so frustrating when people can't or won't speak the same language as you (i.e. your pool builder's apparent lack of knowledge about plaster and pool chemistry). Doubly frustrating when large amounts of money are involved!
Absolutely!! I have a hard time communicating "pool talk" with my husband now - [emoji14]
[emoji176] Lisa P.
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[emoji176] Lisa P.
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Yes, it was a lot of money and I'm rather upset. I'm probably going to get help from the commercial pool guy. Hopefully the builder will come through with that sense and dispense. I think the plaster is in trouble because it's much darker and spottier in some areas than others.
I mean over the last three days it's been three and a quarter jugs of dry acid and the pH is still at about 8. It's really insane.